The Tamil National People's Front's (TNPF) Amparai District candidate, Kokularaj, was attacked with swords by men from the paramiltary Karuna group shortly after midnight, the TNPF tweeted.
Kokularaj has been admitted to hospital with serious injuries.
In the run up to Sri Lanka's parliamentary elections, TNPF leader, Gajendrakumar Ponnambalam reported that candidates who were contesting in the Eastern province are “on the verge of withdrawing due to ferocious threats and harassment” from paramilitary groups.
Ponnambalam said that paramilitary organisations and Sri Lankan military intelligence had pursued a campaign of intimidation and harassment against party members.
"In Amparai 3 of our candidates are on the verge of withdrawing due to ferocious threats and harassment from the Karuna group,” he said. “In Batticaloa, one of our candidates is under threat from Pillayan group for the last 3 years," he added.